ROM Compatibility
5 messages · 2003-09-13 → 2003-11-07 · Yahoo Group era · View archive on archive.org
Participants: Alvin, Tarquin Mills, Stephen Wenzler, joe schmoe
Preserved from the Timex/Sinclair 2068 Yahoo Group (2001–2019), which is no longer online. Text reproduced from the archive.org archive; email addresses masked.
Messages
1. ROM Compatibility
Tarquin Mills · Sat, 13 Sep 2003 21:10
Hello
I am a newbie to Timex Sinclairs, why did Timex (or anyone later) not
use the empty 4KB of the standard ROM to add the new commands, like other
modified ROMs?
--
Tarquin Mills
Norwich Spectrum and SAM Show (ORSAM 2003)
http://homepage.ntlworld.com/speccyverse/orsam.htm
2. Re: [ts2068] ROM Compatibility
Stephen Wenzler · Sat, 13 Sep 2003 17:07
Let me tell you clearly that the TS2068 have two ROMs and 48K of RAM so
therefore the first 16K of RAM is taken up by the HOME ROM and the
other small block of memory is set aside for video and another block
reserved for variables and so on -- if you search the net, I'm sure you
will learn how the memory is mapped so the EXROM is only mapped into
place and out and contains most of I/O operations and that is quite
complicated for you.
Tarquin Mills wrote:
> Hello
> I am a newbie to Timex Sinclairs, why did Timex (or anyone later) not
> use the empty 4KB of the standard ROM to add the new commands, like other
> modified ROMs?
> --
> Tarquin Mills
>
> Norwich Spectrum and SAM Show (ORSAM 2003)
> http://homepage.ntlworld.com/speccyverse/orsam.htm
>
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3. Re: [ts2068] ROM Compatibility
Alvin · Thu, 18 Sep 2003 16:00
Tarquin Mills wrote:
>
> Hello
> I am a newbie to Timex Sinclairs, why did Timex (or anyone later) not
> use the empty 4KB of the standard ROM to add the new commands, like other
> modified ROMs?
> --
> Tarquin Mills
4K of extra space? I only spot 1170 bytes of free space in the 48K
Spectrum ROM. Even 4K may not have been enough for what Timex
had planned for the ROM.
The TS2068's operating system was supposed to support 256 banks
of 64K devices where a device could be RAM (so a total of 16MB
possible) or an intelligent device. The device would be able
to inform the operating system about how to set it up and add
basic streams to control it.
Alvin
4. Re: [ts2068] ROM Compatibility
joe schmoe · Wed, 5 Nov 2003 14:01:
Is this the same 4k area that has scattered remnants
of disk I/O code through it? This may be the code that
Timex didnt perfect in time to get the 2068 on the
shelf, or...was paid by "Big Blue" not to....hmmmm.
neil
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5. Re: [ts2068] ROM Compatibility
Alvin · Fri, 07 Nov 2003 15:23
joe schmoe wrote:
>
> Is this the same 4k area that has scattered remnants
Ah, yes, just reread the original message and probably
missed the point. The 48K Spectrum ROM had just 1170
bytes free in its 16K ROM and the reason I mentioned
that is that Timex started with it and added modifications,
modifications whose scope clearly increased as the
ts2068 was being pushed rather than a straight Spectrum
clone.
There is a sizeable chunk of available space in the ts2068's
home ROM, but remember that's after Timex had already
moved tape i/o code and a few phases of initialization
into the 8K EXROM bank. This wouldn't fit into the
HOME bank by itself. And then you have to keep in mind
that the o/s wasn't complete and was planned to be
completed after the first version was already rolling
off the assembly lines. Hence the socketed ROMs which
would have been easily replaceable with completed
firmware when that was made available. The extra space
afforded by the 8K EXROM bank gave adequate breathing
room for future upgrades.
> of disk I/O code through it? This may be the code that
> Timex didnt perfect in time to get the 2068 on the
> shelf, or...was paid by "Big Blue" not to....hmmmm.
I haven't seen disk i/o code but there is definitely
support for smart peripherals that may have included
disks. The "Big Blue" thang is all too conspiracy
theory for me :-) Timex just made an error in judgement
IMO. They though the home computer market collapse was
at the beginning rather than the end and expected 1984
to be yet another disaster when in fact it was just
the opposite. What a shame they ignored the Spectrum's
success in Europe when they chose to close the computer
division.
Alvin